One of the best and enduring aspects of presidential cabinets has been the willingness of many chief executives to appoint at least one member from the opposition party. The practice demonstrates bipartisanship and also gives the president access to views that may not always be offered by loyalist appointees.

The custom of reaching across the party aisle has been brought into question by the
new memoir of former Secretary of Defense Robert Gates, kept in the job by President Obama as a carryover from the George W. Bush presidency. Gates' attacks on Obama's leadership and on other members of his team have cast him somewhat curiously as a silent fox in the chicken coop.

He was admitted to the Obama inner circle and rather than openly blowing the whistle on presidential decisions with which he strongly disagreed, he chose to keep the depth of his dissent to himself until after his retirement and was back in private life.

His decision to save his gripes for the memoir may tarnish his own reputation as a straight-talking public servant ready to offer his advice regardless of party. There has been no indication that Gates' apparent reticence had anything to do with the fact he is a longtime Republican.

Rather, it comes through as the disappointment of a Pentagon chief with what he saw as a faulty Obama commitment to the Americans in uniform he sent to war in Afghanistan, and to the mission on which he risked their lives. The sentiment is an understandable one, but it should not have inhibited his candor, to which the president was entitled at the time.

Gates' post-retirement observations on Obama and members of his national security team put a coat of pettiness on his own image of a man who had completed a lifetime of public service above personal sniping and grudge-settling. As he goes through the customary book tour, he will find himself repeatedly defending himself as much as justifying the criticisms he has offered in print.

Fortunately, history is replete with bipartisan and nonpartisan appointments to presidential cabinets in both parties, so Gates' tell-all is likely only to have a temporary effect on the practice. But his memoir could lead future presidents to extract promises from appointees not to take pen in hand at least until their presidencies are over.

One of the most puzzling aspects of the Gates authorship is his confession that he despised his job as defense secretary and couldn't wait to leave it. Yet for all his raps against Obama, Gates wrote that he believed the Democratic president had made the right decisions on Afghanistan.

Thus he comes off as more a caviler -- one who quibbles over annoying irritations -- than as a tough truth-teller. In any event, he won't have to worry about being asked to be part of any future Democratic administration.

The remaining Republican in the Obama cabinet, the second-term defense secretary Chuck Hagel, won't be writing any such sequel to Gates' uncharacteristic rant.

The former Nebraska senator shared the reservations about Bush's war in Afghanistan held by Vice President Joe Biden when both served on the Senate Foreign Relations Committee. After a stormy Senate confirmation, Hagel has kept a low-profile as Pentagon boss.

This penchant of former cabinet members and other high government officials to rush their bursts of candor into print seldom does honor to the authors in the end.

An exception was the late Robert McNamara, defense secretary to John Kennedy and Lyndon Johnson, whose memoir of the Vietnam War years was written two decades later.

McNamara wrote with uncommon humility: "People are human; they are fallible. I concede with painful candor and a heavy heart that the adage applies to me. ... Although we sought to do the right thing -- and believed we were doing the right thing -- in my judgment, hindsight proves us wrong. ... External military force cannot substitute for the political order and stability that must be forged by a people for themselves."

Better late then never, McNamara's memoir did not compensate for the tragedy to which his decisions contributed. But at least it sought to restore the integrity of the man himself, which may be the best such a confession can ever do.